Ocean barrier layers' effect on tropical cyclone intensification
Ocean barrier layers' effect on tropical cyclone intensification
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DOI：
10.1073/pnas.1201364109
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发表时间：
2012-09-04
影响因子：
11.1
通讯作者：
Hsieh, Jen-Shan
中科院分区：
文献类型：
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作者：
Balaguru, Karthik;Chang, Ping;Hsieh, Jen-Shan
改善热带气旋的预报和减轻其破坏潜力需要了解影响气旋路径和强度的各种环境因素。在这里，使用相结合的观测和模式模拟，我们系统地表明，热带气旋加强显着影响盐度引起的障碍层，这是“准永久性”的功能，在热带海洋上层。当热带气旋经过有障碍层的地区时，障碍层内的层化和稳定性增加，减少了风暴引起的垂直混合和海面温度冷却。这导致从海洋到大气的焓通量增加，从而导致热带气旋的加强。平均而言，热带气旋加强率在有障碍层的地区比没有障碍层的地区高出近50%。我们的发现，这强调了不仅要观察上层海洋的热结构，而且还在热带屏障层深区域的盐度结构的重要性，可能是一个关键，更熟练的预测热带气旋强度，通过改进海洋状态估计和模拟屏障层过程。由于水文循环对全球变暖作出反应，因此在预测未来热带气旋活动时必须考虑障碍层分布的任何相关变化。
Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.